Unitary blade seal for a shearing blind ram in a ram type blowout preventer

ABSTRACT

A unitary blade seal for a shearing blind ram of a ram-type blowout preventer is disclosed and includes an elongate member having a generally semi-circular cross section with a curved upper surface and a lower surface. The lower surface has a pair of laterally extending sides that taper outwardly and have a metal outer cap bonded thereto. The metal outer caps form an acute angle that engages a complementary groove formed in the upper ram of the shearing blind ram assembly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a unitary, i.e., one piece, blade seal for usein a shearing blind ram for a ram-type blowout preventer used in oil andgas drilling operations. Ram-type blowout preventers are part of apressure control system used in oil and gas drilling operations tocontrol unexpected well bore pressure spikes or kicks as they arecommonly referred to in the industry.

The blowout preventer has a body with a vertical bore and a pair oflaterally disposed opposing bonnet assemblies. Each bonnet assemblyincludes a piston which is laterally moveable within the bonnet assemblyby pressurized hydraulic fluid. Replaceable sealing elements calledpackers are mounted on the ends of the pistons which extend into theblowout preventer bore. When these pistons are moved to a closedposition, commonly referred to as “closing the blowout preventer” or“closing the rams”, the vertical bore of the blowout preventer is sealedand the kick is contained. These packers are available in a variety ofconfigurations designed to seal the blowout preventer bore when theopposing pistons are moved to their closed position. One type of packerhas ends designed to seal around pipe of a specific size in the blowoutpreventer bore when the blowout preventer is closed. Other rams aredesigned to shear through a drill pipe section extending through thevertical bore and seal off the bore. It is this type, commonly referredto as blind shear rams and the blade seal to be used therein to whichthe present invention is directed.

These shearing blind rams face a formidable task. They must be able toshear through a piece of drill pipe in the blowout preventer bore andthen seal against each other to contain the well bore pressure during akick. The shearing blind rams must form a pressure tight seal during akick until the well bore pressure can be controlled which can reachseveral thousand pounds per square inch. The shearing blind ram hasvarious rubber seal elements attached to it to ensure a complete seal ofthe blowout preventer bore.

These seal elements, including the blade seal of the present invention,are exposed to tremendous well bore pressures. The blade seal of thecurrent invention offers a substantial improvement by offering a simple,easy to manufacture blade seal that minimizes wear and tear of theelastomeric seal element with a pair of end caps to minimize extrusionof the seal element.

2. Description of Related Art

Various types of shearing blind rams with various blade seals have beenshown and used.

U.S. Pat. No. 3,766,979 to J. T. Petrick shows a well casing cutteruitilizing O rings to seal around the casing being cut.

The ram-type blowout preventer shown in U.S. Pat. No. 3,817,326 to M. J.Meynier III discloses a blade seal with the rubber element bonded to ametal member.

U.S. Pat. No. 4,081,027 to T. X. T. Nguyen. shows a shearing ram forhydrogen sulfide service utilizing a rubber element bonded to the shearram to seal after shearing.

The wellhead shearing apparatus shown in U.S. Pat. No. 4,341,264 to F.H. Cox et al. discloses a rubber element bonded in a recessed groove ina shearing ram to act as a blade seal.

U.S. Pat. No. 4,347,898 to M. R. Jones shows a shear ram blowoutpreventer utilizing a rectangular seal in the lower face of the upperram as a blade seal.

A shearing ram utilizing a pair of hardened points to aid in initiatingthe shearing action is shown in U.S. Pat. No. 4,537,250 to J. N.Troxell, Jr. A plain rectangular seal acts as a blade seal.

The shear ram apparatus shown in U.S. Pat. No. 4,540,046 to S. W.Granger et al. discloses a blade seal with the rubber element bonded toa metal member.

U.S. Pat. No. 5,005,802 to D. J. McWhorter et al. shows a variable borepacker for a ram type blowout preventer.

U.S. Pat. No. 5,360,061 to L. M. Womble shows a blowout preventer withtubing shear rams designed to control the shape of the sheared pipe end.

The shear ram apparatus shown in U.S. Pat. No. 5,515,916 to T. D. Haleydiscloses a blade seal with the rubber element bonded to a metal memberand a metal insert in the rubber element to aid in sealing.

U.S. Pat. No. 5,713,581 to D. W. Carlson et al. shows a blade seal ofnitrile rubber with uniformly dispersed synthetic, non-cellulosic fibersto aid in preventing seal rollover.

U.S. Pat. No. 6,158,505 to R. Araujo shows a blade seal design utilizinga pair of tapered blade seal elements to effectuate sealing.

SUMMARY OF THE INVENTION

The blade seal for a shearing blind ram of the present invention isdesigned for use in a standard ram-type blowout preventer used in oiland gas drilling operations. The blowout preventer has a body with anaxial bore, a pair of opposing bonnet assemblies and a pair of opposingrams laterally moveable within the bonnet assemblies by a pressurizedfluid source to control flow of well fluids through the blowoutpreventer body axial bore. The blade seal includes an elongate memberhaving a generally semi-circular cross section with a curved uppersurface and a substantially flat lower surface. The flat lower surfacehas a pair of laterally extending sides that taper outwardly and have ametal outer cap bonded thereto. The metal outer caps form an acute anglethat engages a complementary groove formed in the upper ram of theshearing blind ram assembly. The opposing lower ram has a upwardlyfacing surface that seals against the blade seal after the pipe issheared.

A principal object of the present invention is to provide a unitaryblade seal for use in shearing blind rams that has an improved lifecycle and fits in existing blowout preventers.

These with other objects and advantages of the present invention arepointed out with specificness in the claims annexed hereto and form apart of this disclosure. A full and complete understanding of theinvention may be had by reference to the accompanying drawings anddescription of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention are setforth below and further made clear by reference to the drawings,wherein:

FIG. 1 is a perspective view with a cutaway section of a shearing blindram assembly utilizing the blade seal of the present invention installedin a typical ram-type blowout preventer used in oil and gas drillingoperations.

FIG. 2 is an exploded view of the shearing blind ram assembly.

FIG. 3 is a partially exploded view of the upper ram of a shearing blindram assembly shown in an inverted position.

FIG. 4 is a perspective view of the blade seal of the present invention.

FIG. 5 is an elevation view showing the shearing blind ram assemblyafter closing of the blowout preventer and the blade seal sealingbetween the upper and lower rams.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the drawings, and particularly to FIG. 1, an isometricview of a ram type blowout preventer 10 used in oil and gas drillingoperations is shown. The ram type blowout preventer 10 includes a bodyor housing 12 with a vertical bore 14 and laterally disposed ramguideways 16. Bonnet assemblies 18 are mounted to the body 12 with bolts20 and aligned with laterally disposed guideways 16. Each bonnetassembly 18 includes an actuation means 22, including a piston 24 andconnecting rod 26. While only one guideway 16 and actuation means 22 isshown, it is understood by those of ordinary skill in the art that thereis a pair of opposed guideways 16 and actuation means 22. Eachconnecting rod 26 is connected to a shearing blind ram assembly 28.Shearing blind ram assembly 28 includes a blade seal 30 of the presentinvention. Actuation means 22 allows ram and shearing blind ram assembly28 to be reciprocated within guideways 16.

Shearing blind ram assembly 28 is shown in an exploded view in FIG. 2 toaid in understanding the relationship between the parts. Shearing blindram assembly 28 includes lower ram 32 and upper ram 34. Lower ram 32includes top seal 36 and side seals 38 that seal against guideways 16.Lower ram 32 includes shear blade 40 positioned on its leading edge andseal surface 42. Upper ram 34 includes top seal 44 and side seals 46that seal in guideways 16 in a manner similar to lower ram 32. Bladeseal 30 is positioned on the lower face of upper ram 34.

Referring to FIG. 3, upper ram 34 is shown inverted from its position ofFIG. 2 to better illustrate the positioning of blade seal 30 therein. Atrapezoidal or “dove tail” shaped groove 48 are machined in lower face50 of upper ram 34. Trapezoidal or “dove tail” shaped groove 48 extendsthe full width of upper ram 34.

As best seen in FIG. 4, blade seal 30 includes a generally elongatemember 52 formed of molded rubber or other suitable elastomeric materialhaving a generally semi-circular cross section 54. Semi-circular crosssection 54 has a curved upper surface 56 and substantially flat lowersurface 58. Flat lower surface 58 has a pair of laterally extendingsides 60 that taper outwardly from semi-circular cross section 54. Outercaps 62 are bonded to laterally extending sides 60 in a manner wellknown to those of ordinary skill in the art. Outer caps 62 are formed ofmetal or similarly suitable stiff material and positioned at an acuteangle for engagement with complementary trapezoidal or “dove tail”shaped groove 48 in upper ram 34 to ensure blade seal 30 is heldsecurely in position.

A typical sequence of operation is as follows. With shearing blind ramassembly 28 installed in blowout preventer 10, the rams are closed. Thiscauses pipe 64 to be sheared and lower face 50 of upper ram 34 and sealsurface 42 of lower ram 32 to slide over one another in close fittingrelationship. Continued movement causes seal surface 42 of lower ram 32to contact and seal against curved upper surface 56 of blade seal 30 asbest seen in FIG. 5. Top seals 36 and 44 and side seals 38 and 46 alsoseal against guideways 16 to ensure a complete seal of the vertical bore14 after shearing.

The construction of my unitary blade seal for a shearing blind ram willbe readily understood from the foregoing description and it will be seenthat I have provided a unitary blade seal that has an improved lifecycle and fits in existing blowout preventers. Furthermore, while theinvention has been shown and described with respect to certain preferredembodiments, it is obvious that equivalent alterations and modificationswill occur to others skilled in the art upon the reading andunderstanding of the specification. The present invention includes allsuch equivalent alterations and modifications, and is limited only bythe scope of the appended claims

1. A ram-type blowout preventer for oil and gas drilling operationsincluding a shearing blind ram, comprising: a body with a vertical bore;a pair of opposing bonnet assemblies laterally disposed in said body; apair of opposing shearing blind rams laterally moveable within saidbonnet assemblies; a blade seal for sealing against an opposing shearingblind ram disposed in one of said shearing blind rams, said blade sealhaving a generally semi-circular cross section; said generallysemi-circular cross section having a curved upper surface and a lowersurface, said lower surface having a pair of laterally extending sides,said pair of laterally extending sides each having a outer cap; and,said generally semi-circular cross section is molded of rubber.
 2. Aram-type blowout preventer for oil and gas drilling operations includinga shearing blind ram according to claim 1, wherein: each of said pair oflaterally extending sides tapering outwardly from said semi-circularcross section.
 3. A ram-type blowout preventer for oil and gas drillingoperations including a shearing blind ram according to claim 2, wherein:said outer caps are bonded to said laterally extending sides.
 4. Aram-type blowout preventer for oil and gas drilling operations includinga shearing blind ram according to claim 3, wherein: said outer caps areformed of metal.
 5. A ram-type blowout preventer for oil and gasdrilling operations including a shearing blind ram according to claim 4,wherein: said outer caps bonded to said laterally extending sides toform an angle for engagement with a complementary groove formed in saidshearing blind ram.
 6. A ram-type blowout preventer for oil and gasdrilling operations including a shearing blind ram according to claim 5,wherein: said curved upper surface of said generally semi-circular crosssection extends above said outer caps.
 7. A ram-type blowout preventerfor oil and gas drilling operations including a shearing blind ramaccording to claim 6, wherein: said angle between said outer caps bondedto said laterally extending sides is an acute angle.
 8. A shearing blindram assembly for a ram-type blowout preventer used in oil and gasdrilling operations, comprising: an upper ram and a lower ram; saidupper ram and said lower ram including top seals and side seals forsealing in a guideway of a ram-type blowout preventer; a blade sealpositioned on the lower face of said upper ram; said lower ram includinga seal surface for engagement with said blade seal when said shearingblind ram assembly is closed; said blade seal having a generallysemi-circular cross section; said generally semi-circular cross sectionhaving a curved upper surface and a lower surface, said lower surfacehaving a pair of laterally extending sides, said pair of laterallyextending sides each having a outer cap; and, said generallysemi-circular cross section is molded of rubber.
 9. A shearing blind ramassembly for a ram-type blowout preventer used in oil and gas drillingoperations according to claim 8 wherein: each of said pair of laterallyextending sides tapering outwardly from said semi-circular crosssection.
 10. A shearing blind ram assembly for a ram-type blowoutpreventer used in oil and gas drilling operations according to claim 9,wherein: said outer caps are bonded to said laterally extending sides.11. A shearing blind ram assembly for a ram-type blowout preventer usedin oil and gas drilling operations according to claim 10, wherein: saidouter caps are formed of metal.
 12. A shearing blind ram assembly for aram-type blowout preventer used in oil and gas drilling operationsaccording to claim 11, wherein: said outer caps bonded to said laterallyextending sides to form an angle for engagement with a complementarygroove formed in said shearing blind ram.
 13. A shearing blind ramassembly for a ram-type blowout preventer used in oil and gas drillingoperations according to claim 12, wherein: said curved upper surface ofsaid generally semi-circular cross section extends above said outercaps.
 14. A shearing blind ram assembly for a ram-type blowout preventerused in oil and gas drilling operations according to claim 13, wherein:said angle between said outer caps bonded to said laterally extendingsides is an acute angle.
 15. A blade seal for a shearing blind ram for aram-type blowout preventer used in oil and gas drilling operations,comprising: an elongate member having a generally semi-circular crosssection; said generally semi-circular cross section having a curvedupper surface and a lower surface, said lower surface having a pair oflaterally extending sides, said pair of laterally extending sides eachhaving a outer cap; and, said generally semi-circular cross section ismolded of rubber.
 16. A blade seal for a shearing blind ram for aram-type blowout preventer used in oil and gas drilling operationsaccording to claim 15, wherein: each of said pair of laterally extendingsides tapering outwardly from said semi-circular cross section.
 17. Ablade seal for a shearing blind ram for a ram-type blowout preventerused in oil and gas drilling operations according to claim 15, wherein:said outer caps are bonded to said laterally extending sides.
 18. Ablade seal for a shearing blind ram for a ram-type blowout preventerused in oil and gas drilling operations according to claim 17, wherein:said outer caps are formed of metal.
 19. A blade seal for a shearingblind ram for a ram-type blowout preventer used in oil and gas drillingoperations according to claim 18, wherein: said outer caps bonded tosaid laterally extending sides to form an angle for engagement with acomplementary groove formed in said shearing blind ram.
 20. A blade sealfor a shearing blind ram for a ram-type blowout preventer used in oiland gas drilling operations according to claim 19, wherein: said curvedupper surface of said generally semi-circular cross section extendsabove said outer caps.
 21. A blade seal for a shearing blind ram for aram-type blowout preventer used in oil and gas drilling operationsaccording to claim 20, wherein: said angle between said outer capsbonded to said laterally extending sides is an acute angle.